Technical Field
The present invention relates to an integrated method of determining the location and the type of damage in casing or tubing of a wellbore. The method involves recording a thickness profile, a temperature log, and a noise log along the well, and further locating the damage from the thickness profile, along with determining the type of damage from the temperature log and the noise log.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Effective well integrity practices ensure the protection of people, facilities and the environment from the risk of uncontrolled release of formation fluids throughout the life cycle of a well, so petroleum engineers are always required to ensure well integrity. Part of well integrity is to make sure downhole equipment and barriers are in excellent condition. Discovering the downhole leak source of pressure communication between tubing-casing and casing-casing annuli in any well, particularly at early stages, is a huge challenge for the oil industry and the key to well integrity management.
Subsurface well integrity is important for any type of well to avoid the risk of uncontrolled release of formation fluids throughout the life cycle of that well which is necessary for both protecting the environment and health of people. The currently employed techniques to locate well anomalies is not sufficiently reliable, therefore, a reliable methodology is needed to identify any small source of downhole leaks.
Thickness profile (or thickness log) offers valuable visions to ensure the effective application of safety and environmental regulations. Thickness profile can be obtained by a mechanical caliper tool which is used to detect the internal condition of a pipe (e.g. tubing or casing). Its log results are affected by scale build up on the internal wall. Thickness profile can also be obtained by an electromagnetic tool which is used to detect a pipe inner diameter and to compare it with the actual inner pipe diameter. It consists of transmitters and receivers to generate the thickness profiles. Thickness profile can also be obtained by an ultrasonic acoustic tool. The tool generates high frequency ultrasonic pulses through a pipe (e.g. tubing or casing) wall. The amplitude and travel time of echoes are used to generate a thickness profile. Thickness profile can be used to locate damage zones in the tubing and/or casing, or to evaluate the condition of tubing and/or casing.
Temperature log is one of the reliable logs for leak detection. The classical procedure is to obtain a true geothermal temperature profile and correlate future temperature changes to the geothermal temperature profile to obtain an estimate of the location, magnitude and direction of the cross-flow anomalies. It indicates the presence of flow from its static or geothermal value. Under static conditions, temperature increases gradually with depth. The nature of well completion also influences the method in which temperature returns to its geothermal value. A good knowledge of the geothermal gradient is necessary for having representative interpretation. Interpretation of temperature logging was observed for flow measurements and studied by Nowak in 1953. In 1969 and 1979, Cocanwer and Romero-Juarez respectively have provided similar approaches. The purpose of temperature log is to identify any cross flow and abnormal geothermal phenomena.
Noise log is a record of a passive measure of the noticeable sound detected by sensitive hydrophones at a number of locations in the wellbore. It is designed to record sounds in specific frequency range based on the design tool. In 1955 Enright introduced noise log as a qualitative indicator of channeling behind pipe. This concept describes the procedure of locating tubing and casing leaks with acoustic recorder which detect the highest noise level at leaks. In 1970 Korotaev used a noise detector to identify gas bearing zones in uncased well. In 1994 McKinley introduced a noise logging technology based on the recording of acoustic noise into several frequency channels and presented the results of his own experimental research. Later on with noise technology development, noise log started to be used quantitatively to estimate flow rates in some instances, and its application has been extended beyond channel detection.
In view of the forgoing, one objective of the present invention is to develop an integrated and rigless method for determining location and type of a damage in casing or tubing of a wellbore using thickness profile (or thickness log), temperature log, and noise log.